Prepared in cooperation with the Great Lakes Restoration Initiative

Hydraulic and Water-Quality Data Collection for the 

Investigation of Great Lakes Tributaries for Asian Carp 

Spawning and Egg-Transport Suitability

Scientific Investigations Report 2013–5106

U.S. Department of the Interior

U.S. Geological Survey
Cover images: 

Upper left: U.S. Geological Survey (USGS) personnel collecting data on the Sandusky River, September 2012. (Photograph by 

David Straub, USGS)

Upper right: USGS personnel collecting data on the Milwaukee River, July 2010. (Photograph by Leah Kammel, USGS)

Lower left: Boat set-up with acoustic Doppler current profiler, water-quality probe, and global positioning system for data 

collection on the Milwaukee River, July 2010. (Photograph by Rob Waschbusch, USGS)

Lower right: Grafton Dam on the Milwaukee River, August 2010. (Photograph by Rob Waschbusch, USGS)
Hydraulic and Water-Quality Data 

Collection for the Investigation of 

Great Lakes Tributaries for Asian Carp 

Spawning and Egg-Transport Suitability 

By Elizabeth A. Murphy and P. Ryan Jackson

Prepared in cooperation with the Great Lakes Restoration Initiative

Scientific Investigations Report 2013–5106

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

Murphy, E.A., and Jackson, P.R., 2013, Hydraulic and water-quality data collection for the investigation of Great Lakes 

tributaries for Asian carp spawning and egg-transport suitability: U.S. Geological Survey Scientific Investigations 

Report 2013–5106, 30 p., http://pubs.usgs.gov/sir/2013/5106/.
iii

Contents

Acknowledgments........................................................................................................................................vi

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Objective and Scope .....................................................................................................................................2

Site Selection..................................................................................................................................................4

Methodology...................................................................................................................................................6

Target River Conditions and Sampling Locations............................................................................6

Measurement Procedures ..................................................................................................................6

Data Collection......................................................................................................................................7

Data Processing..................................................................................................................................11

Settling Velocities and Hatch Times of Asian Carp Eggs ......................................................................11

Spawning and Egg-Transport Suitability Criteria ...................................................................................12

Results ...........................................................................................................................................................13

Tributary Case Studies .......................................................................................................................13

Milwaukee River........................................................................................................................13

St. Joseph River.........................................................................................................................16

Maumee River............................................................................................................................19

Sandusky River...........................................................................................................................23

Critical Velocity for Transport of Water-Hardened Asian Carp Eggs.........................................26

Suggested Future Studies ..........................................................................................................................26

Conclusions...................................................................................................................................................27

References Cited..........................................................................................................................................28

Figures

1. Map showing location of field data collection and other areas of interest .......................3

2. Map showing Lakes Erie, Huron, St. Clair, Michigan, and Superior indicating rivers 

lacking dams and having a minimum length of 100 kilometers, which may be 

suitable for spawning by bighead and silver carp ..................................................................4

3. Graph showing air temperature measured at the General Mitchell International 

Airport in Milwaukee, Wisconsin, and the hydrograph from the Milwaukee River 

at Milwaukee, U.S. Geological Survey streamgage (04087000), showing the field 

sampling period of this study......................................................................................................8

4. Graphs showing air temperature measured at the South Bend Regional Airport 

in South Bend, Indiana, and the hydrographs from the St. Joseph River at Niles, 

U.S. Geological Survey streamgage (04101500), showing the two field sampling 

periods of this study. A, November 30–December 5, 2010. B, September 27–30, 2011.....9

5. Graph showing air temperature measured at the Toledo Express Airport in Toledo, 

Ohio, and the hydrograph from the Maumee River at Waterville, U.S. Geological 

Survey streamgage (04193500), showing the field sampling period of this study............10
iv

6. Graph showing air temperature measured at Toledo Metcalf Field in Toledo, Ohio, 

and the hydrograph from the Sandusky River at Fremont, Ohio, U.S. Geological 

Survey streamgage (04198000), showing the field sampling period of this study............10

7. Graph showing observations of hatching times for silver and bighead carps 

from a range of studies and empirical estimates over a range of temperatures ............13

8. Graphs showing hydraulic and water-quality data for the Milwaukee River, 

Wisconsin, July 21–August 12, 2010........................................................................................14

9. Graphs showing A, mean velocity, B, estimated advection time, and C, shear 

velocity for the Milwaukee River, Wisconsin, July 21–August 12, 2010..............................15

10. Graphs showing hydraulic and water-quality data for the St. Joseph River, 

Michigan and Indiana, November 30–December 5, 2010 (hydraulic data), and 

September 27–30, 2011 (water-quality data)..........................................................................17

11. Graphs showing A, mean velocity, B, estimated advection time, and 

C, shear velocity for the St. Joseph River, Michigan and Indiana, 

November 30–December 5, 2010 (hydraulic data), and 

September 27–30, 2011 (water-quality data)..........................................................................18

12. Graphs showing hydraulic and water-quality data for the Maumee River, Ohio, 

August 25–29, 2011 .....................................................................................................................20

13. Graphs showing A, mean velocity, B, estimated advection time, and C, shear 

velocity for the Maumee River, Ohio, August 25–29, 2011.....................................................21

14. Graphs showing hydraulic and water-quality data for the Sandusky River, Ohio, 

September 11 and 12, 2012........................................................................................................24

15. Graphs showing A, mean velocity, B, estimated advection time, and C, shear 

velocity for the Sandusky River, Ohio, September 11 and 12, 2012......................................25

16. Graph showing theoretical curves for estimating the minimum transport velocity 

for water-hardened Asian carp eggs from observations of mean flow depth and 

substrate type..............................................................................................................................27

Tables

1. Dams on the study reaches ........................................................................................................5

2. Bighead and silver carp egg-settling velocities from Duane Chapman 

(U.S. Geological Survey, unpub. data, 2011), and approximate average 

settling velocities used in the 2013 analysis ..........................................................................12
v

Conversion Factors, Datums, and Abbreviations

Inch/Pound to SI

Multiply By To obtain

Length

mile (mi) 1.609 kilometer (km)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

SI to Inch/Pound

Multiply By To obtain

Length

millimeter (mm) 0.03937 inch (in)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Flow rate

centimeter per second (cm/s) 0.032 foot per second (ft/s)

meter per second (m/s) 3.281 foot per second (ft/s) 

cubic meter per second (m3

/s) 35.31 cubic foot per second (ft3/s)

Hydraulic gradient

meter per meter (m/m) 1 foot per foot (ft/ft)

Temperature in °Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

Specific conductance is given in millisiemens per centimeter (mS/cm).

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L).
vi

Abbreviations

ADCP acoustic Doppler current profiler

CAWS Chicago Area Waterway System

dGPS differentially corrected global positioning system

eDNA environmental DNA

GIS geographic information system

GLMRIS Great Lakes and Mississippi River Interbasin Study

NTU nephelometric turbidity units

u* shear velocity

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey

Acknowledgments

The authors acknowledge the Great Lakes Restoration Initiative for the funding to perform this 

study. The authors also acknowledge the field crews from the U.S. Geological Survey (USGS) 

Michigan, Ohio, and Wisconsin Water Science Centers for collecting the data that made 

this report possible, often in less than ideal field conditions. Finally, the authors gratefully 

acknowledge Duane Chapman of the USGS and his team members for contributing data to this 

report, sharing their knowledge with the authors about the biological aspects of Asian carp, and 

reviewing this report.
Hydraulic and Water-Quality Data Collection for the 

Investigation of Great Lakes Tributaries for Asian Carp 

Spawning and Egg-Transport Suitability

By Elizabeth A. Murphy and P. Ryan Jackson

Abstract

If the invasive Asian carps (bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix) 

migrate to the Great Lakes, in spite of the efforts to stop their 

advancement, these species will require the fast-flowing water 

of the Great Lakes tributaries for spawning and recruitment 

in order to establish a growing population. Two Lake Michigan tributaries (the Milwaukee and St. Joseph Rivers) and 

two Lake Erie tributaries (the Maumee and Sandusky Rivers) 

were investigated to determine if these tributaries possess the 

hydraulic and water-quality characteristics to allow successful spawning of Asian carps. To examine this issue, standard 

U.S. Geological Survey sampling protocols and instrumentation for discharge and water-quality measurements were used, 

together with differential global positioning system data for 

georeferencing. Non-standard data-processing techniques, 

combined with detailed laboratory analysis of Asian carp 

egg characteristics, allowed an assessment of the transport 

capabilities of each of these four tributaries. This assessment 

is based solely on analysis of observed data and did not utilize 

the collected data for detailed transport modeling.

All four tributaries exhibited potential settling zones for 

Asian carp eggs both within the estuaries and river mouths 

and within the lower 100 kilometers (km) of the river. Dams 

played a leading role in defining these settling zones, with the 

exception of dams on the Sandusky River. The impoundments 

created by many of the larger dams on these rivers acted to 

sufficiently decelerate the flows and allowed the shear velocity 

to drop below the settling velocity for Asian carp eggs, which 

would allow the eggs to fall out of suspension and settle on 

the bottom where it is thought the eggs would perish. While 

three rivers exhibited these settling zones upstream of the 

larger dams, not all settling zones are likely to have such 

effects on egg transport. The Milwaukee River exhibited only 

a short settling zone upstream of the Grafton Dam, whereas 

the St. Joseph and Maumee Rivers both had extensive settling 

zones (>5 km) behind major dams. These longer settling zones 

are likely to capture more eggs than shorter settling reaches. 

All four rivers exhibited settling zones at their river mouths, 

with the Lake Erie tributaries having much larger settling 

zones extending more than 10 km up the tributaries. 

While hydraulic data from all four rivers indicated settling of eggs is possible in some locations, all four rivers also 

exhibited sufficient temperatures, water-quality characteristics, 

turbulence, and transport times outside of settling zones for 

successful suspension and development of Asian carp eggs 

to the hatching stage before the threat of settlement. These 

observed data indicate that these four Great Lakes tributaries 

have sufficient hydraulic and water-quality characteristics to 

support successful spawning and recruitment of Asian carps. 

The data indicate that with the right temperature and flow 

conditions, river reaches as short as 25 km may allow Asian 

carp eggs sufficient time to develop to hatching. Additionally, examining the relation between critical shear velocity 

and mean velocity, egg settling appears to take place at mean 

velocities in the range of 15–25 centimeters per second, a 

much lower value than is generally cited in the literature. A 

first-order estimate of the minimum transport velocity for 

Asian carp eggs in a river can be obtained by using mean flow 

depth and river substrate data, and curves were constructed to 

show this relation. These findings would expand the number 

of possible tributaries suitable for Asian carp spawning and 

contribute to the understanding of how hydraulic and waterquality information can be used to screen additional rivers in 

the future.

Introduction

Two species of invasive Asian carps (bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys 

molitrix) are threatening to migrate into the Great Lakes from 

the Mississippi River Basin. If Asian carps become established in the Great Lakes, several tributary rivers may provide 

suitable spawning habitats. Although the carps primarily live 

in slow-moving water, they are thought to require streams 

with sufficient length, velocity, and turbulence to spawn 
2 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

(Kolar and others, 2007). Following spawning, the eggs drift 

in the current while developing. The eggs are slightly heavier 

than water, but remain in the drift because of the turbulence 

of flowing water. If the eggs sink to the bottom and remain 

there, they generally are not thought to survive (Soin and 

Sukhanova, 1972; Yi and others, 1988; Pflieger, 1997). Thus, 

a river with adequate current and reach length to keep the eggs 

adrift until hatching is considered a requirement for reproduction of Asian carps and survival of their eggs. One hundred 

kilometers (km) often is given as a rough estimate of the 

minimum river length required (Krykhtin and Gorbach 1981; 

Yi and others, 1988), but the actual minimum length of river 

would vary among rivers, depending upon variables such as 

water temperature (which controls the developmental rate of 

the eggs), current velocity, and the longitudinal dispersal of 

the eggs in the drift. Also, a minimum current velocity likely 

must be maintained throughout the drift to keep the eggs from 

settling to the river bottom. The values of minimum velocity 

in the literature are based on observations of spawning rivers 

and do not necessarily reflect the minimum velocities required 

to keep eggs in suspension and transport them. The range 

of velocities of rivers where silver carp successfully spawn 

was summarized in Kolar and others (2007) to be from 0.3 to 

3.0 meters per second (m/s). However, Yi and others (2010) 

and Tang and others (1989) suggest the lower limit to velocity 

in spawning rivers is 0.25 m/s.

There have been previous efforts to assess the suitability 

of Great Lakes tributaries for Asian carp spawning and recruitment. Kolar and others (2007) took a geographic information 

system (GIS) analysis approach by characterizing which Great 

Lakes tributaries had undammed lengths greater than 100 kilometers (km). Kocovsky and others (2012) examined temperatures in Lake Erie and its tributaries and analyzed hydraulic 

conditions based on data limited to available U.S. Geological 

Survey (USGS) streamgages. Both studies concluded there 

was high likelihood of the tributaries being used for spawning 

by Asian carps. This study uses a more intensive hydraulic 

approach with data collected along the selected tributaries to 

address the issues of spawning and egg transport.

This report describes the hydraulic and water-quality 

data-collection effort by the USGS, in cooperation with the 

Great Lakes Restoration Initiative as administered by the 

U.S. Environmental Protection Agency, on four Great Lakes 

tributaries and uses new information about egg-transport characteristics to provide insight into the spawning and recruitment 

suitability of these tributaries. This study utilizes recent USGS 

research on Asian carp development, which has quantified 

the relation between development rate and water temperature 

(Chapman and George, 2011) and the settling rates of bighead 

and silver carp eggs (Duane Chapman, U.S. Geological Survey, unpub. data, 2011). The information in this report can be 

used to plan sampling efforts and data analyses in other rivers 

possibly impacted by Asian carps so that control strategies can 

be applied.

Objective and Scope

The objective of this study is to characterize Great Lakes 

tributaries in terms of providing suitable spawning conditions 

for Asian carps and sufficient length and hydraulic conditions 

for eggs to be kept in suspension until hatching. The adequacy 

of rivers for survival of Asian carp in early-life stages is 

thought to depend upon a number of river conditions including 

reach length, channel depth, velocity, shear velocity, channel slope, temperature and turbidity distribution, longitudinal 

dispersion coefficients, and turbulence (Kolar and others, 

2007). Unfortunately, a suitable spawning river cannot simply 

be defined in terms of river length or any single characteristic. 

Rather, what determines if a river is suitable for spawning is 

a complex relation between the hydraulic and water-quality 

characteristics of a river and the egg development stages of a 

particular species. 

This study integrates physical observations and hydraulic 

characteristics from potential spawning rivers with Asian carp 

egg characteristics to evaluate whether successful spawning 

and recruitment is likely in the subject rivers. The biological 

components of this study, which provide information about 

Asian carp egg characteristics used in the hydraulic data 

analysis, are described elsewhere (Chapman and George, 

2011; Amy George and Duane Chapman, U.S. Geological Survey, unpub. data, 2011, 2012; and Duane Chapman, 

U.S. Geological Survey, unpub. data, 2011). Another component of this study, development of a three-dimensional fluvial 

egg transport model (FluEgg) for rapid assessment of potential spawning rivers, also is underway in collaboration with 

the University of Illinois at Urbana-Champaign. This report 

focuses on the final component of this study, the methodology 

for characterization of the spawning suitability of rivers based 

on observed hydraulic and water-quality distributions. Specifically, this report discusses the data collected on the Milwaukee 

River in Wisconsin, the St. Joseph River in Michigan and Indiana, and the Maumee and Sandusky Rivers in Ohio (fig. 1), 

and the processing and analysis of those data for potential 

egg-settling zones and estimates of egg-transport time. 
Objective and Scope 3

0 50 100 MILES

0 50 100 KILOMETERS

Wabash

River

River

90° 88° 86° 84° 82°

42°

40°

ILLINOIS

INDIANA OHIO

WISCONSIN

MICHIGAN

LAKE

MICHIGAN

LAKE

ERIE

ONTARIO

MILWAUKEE RIVER 

MAUMEE 

RIVER

ST. JOSEPH

RIVER

SANDUSKY 

RIVER

LAKE

HURON

CHICAGO 

AREA 

WATERWAYS

Illinois

0408700–Milwaukee 

River at Milwaukee, Wis.

04198000–

Sandusky River 

at Fremont, Ohio

Electric fish barrier

Eagle Marsh

Toledo Express 

Airport

Milwaukee, General 

Mitchell International 

Airport

South Bend

Regional 

Airport 04193500–

Maumee River at 

Waterville, Ohio

04101500–St. Joseph 

River at Niles, Mich. Toledo, 

Metcalf Field

EXPLANATION

04193500–Maumee River at 

Waterville, Ohio

Eagle Marsh

Great Lakes drainage basin

River reach studied and name

U.S. Geological Survey streamgaging station with number and name

National Weather Service station and name

Point of interest and name

MAUMEE RIVER

Toledo, Metcalf Field

Chicago Sanitary

and Ship Canal

Des Plaines River

Figure 1. Location of field data collection and other areas of interest.
4 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

Site Selection

To date, the greatest resource for information about 

potential spawning rivers has been Kolar and others (2007), 

which contains a map of 22 rivers that may meet the 100 km 

free-flowing criteria for spawning (fig. 2). However, this 

map was based solely on a GIS analysis of river length, and 

although it incorporated available dam-inventory information, 

that information is currently (2013) out of date due to dam 

removals since that analysis. Dams have the potential to block 

fish from moving upstream and, therefore, shorten the accessible length of river for the carps. In addition, dams generally 

decelerate the flow, which can settle eggs out of suspension. 

The majority of the dams on the present study reaches are 

either low enough for Asian carps to pass over or have fish 

passages installed (table 1). 

The Great Lakes and Mississippi River Interbasin Study 

(GLMRIS) has identified numerous potential interbasin pathways for aquatic-nuisance species in the Chicago Area Waterway System (CAWS) (U.S. Army Corps of Engineers, 2012a). 

An electric fish barrier was erected on the CAWS upstream of 

the confluence with the Des Plaines River to prevent invasive 

species movement between the two basins (fig. 1). The selection of the tributaries for data collection in the first year of the 

study (2010) was based on proximity to the CAWS, which 

is perceived to be the greatest threat for interbasin transfer 

between the Mississippi and Great Lakes River Basins (fig. 1). 

After looking at the Lake Michigan tributaries close to the 

entry of the CAWS, the Milwaukee River was chosen because 

the proposed removal of Grafton Dam or the addition of a 

fish passage to the dam would give it sufficient reach length 

(Ozaukee County, 2012), and the St. Joseph River was chosen 

because of its sufficient fish-passable length.

22

21

20

19

18

17

16

13

14

15

12

11

10

9

8

7 6

5 4 3

2

1

1 - Conneaut Creek

2 - Grand River

3 - Black River

4 - Vermilion River

5 - Huron River

6 - Portage River

7 - Maumee River

8 - River Raisin

9 - Belle River

10 - Black River

11 - Saginaw River

12 - West Branch Rifle River

13 - Pere Marquette River

14 - Grand River

15 - Saint Joseph River

16 - Sheboygan River

17 - Manitowoc River

18 - Big Cedar River

19 - Ford River

20 - Ontonagon River

21 - Bad River

22 - Nemadji River

LAKE SUPERIOR

LAKE HURON

LAKE

MICHIGAN

LAKE ERIE

WISCONSIN

MICHIGAN

MICHIGAN

ILLINOIS

INDIANA

OHIO

MINNESOTA

CANADA

PENNSYLVANIA

0 5 25 0 100

Miles

0 5 25 0 100 Kilometers

EXPLANATION

Figure 2. Lakes Erie, Huron, St. Clair, Michigan, and Superior indicating rivers lacking dams and having a minimum length of 

100 kilometers, which may be suitable for spawning by bighead and silver carp. (From Kolar and others, 2007.)
Site Selection 5

Table 1. Dams on the study reaches.

[km, kilometer; m, meter; Wis., Wisconsin; Ind., Indiana; Mich., Michigan; data provided by the Wisconsin Department of Natural Resources (DNR), 

the Michigan DNR, and the Ohio DNR]

Dam name River City and State Distance 

(km)

Height 

(m)

Hydraulic 

height 

(m)

Fish 

passable

West Bend

Grafton (Bridge Street Dam)

Thiensville

Kletzsch Park

Estabrook Park

Ball Band Dam

South Bend Dam

French Paper Company Dam

Buchanan

Berrien Springs Dam

Independence Dam

Grand Rapids Dam

Providence Dam

Ballville Dam

Milwaukee

Milwaukee

Milwaukee

Milwaukee

Milwaukee

St. Joseph

St. Joseph

St. Joseph

St. Joseph

St. Joseph

Maumee

Maumee

Maumee

Sandusky

West Bend, Wis.

Grafton, Wis.

Thiensville, Wis.

Glendale, Wis.

Shorewood, Wis.

Mishawaka, Ind.

South Bend, Ind.

Niles, Mich.

Berrien Springs, Mich.

Berrien Springs, Mich.

Defiance, Ohio

Grand Rapids, Ohio

Providence, Ohio

Fremont, Ohio

107.9

48.1

31.9

16.6

11.1

97.5

90.4

69.6

54.7

38.8

97.5

52.4

52.4

25.7

4

6.1

4

2.4

4.6

3

3.7

6.7

4.3

11

3.6

2.4

2.6

10.5

2.1

3.7

1.8

1.2

2.4

2

0

6.7

4.1

11

3.6

2.4

2.6

7.4

Y

N

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

N

In addition to the CAWS potential connections, the 

GLMRIS Other Pathways Preliminary Risk Characterization found 31 potential connections between the 2 basins, of 

which 18 were deemed a large enough risk to warrant more 

in-depth study (U.S. Army Corps of Engineers, 2010). One 

potential connection identified between the Mississippi River 

Basin and the Great Lakes Basin is located in Eagle Marsh 

near Fort Wayne, Indiana. This connection was singled out 

by the U.S. Army Corps of Engineers (USACE) GLMRIS as 

the highest risk, outside of the CAWS, for aquatic-nuisance 

species transfer between the two basins. During high water, 

Eagle Marsh can connect the Wabash River, which contains 

Asian carps, with the Maumee River, which is a tributary to 

Lake Erie (fig. 1). A chain-link fence was erected in October 

2010 to prevent adult Asian carps from entering the Maumee 

River from the Wabash River (U.S. Army Corps of Engineers, 

2010), but that fence does not prevent eggs or small, juvenile 

fish from moving between the basins.

Water samples are collected in the CAWS upstream of the 

electric fish barrier to analyze for bighead and silver carp environmental DNA (eDNA), which is used as an indicator that 

Asian carps may have been present in that location. The eDNA 

results for the CAWS sampling in 2012 are 119 samples positive for silver carp out of 1,110 samples collected. There were 

no samples positive for bighead carp eDNA above the electric 

barrier (U.S. Army Corps of Engineers, 2012b). In June 2012, 

a bighead carp was caught by a commercial fisherman in 

Lake Calumet, which is part of the CAWS system. No other 

bighead or silver carp have been caught above the electric barrier as part of the USACE surveillance efforts. Water samples 

for eDNA analysis also were collected by the Ohio Department of Natural Resources, Michigan Department of Natural 

Resources, U.S. Fish and Wildlife Service, and the USACE in 

the Maumee Bay and River and the Sandusky Bay and River 

during July–August 2012 (Asian Carp Regional Coordinating 

Committee, 2012). Three of 350 samples collected in the Maumee system and 20 of 150 samples collected in Sandusky Bay 

tested positive for silver carp eDNA. Subsequent netting and 

electrofishing efforts in the Maumee and Sandusky systems 

failed to locate any live silver or bighead carp. These eDNA 

results are being used to direct monitoring and planning efforts 

by the many agencies involved with Asian carp control.

The selection of the Maumee River for data collection 

in the second year of the study was based on the potential for 

interbasin transfer at Eagle Marsh in Indiana (fig. 1), which 

can connect the Wabash and Maumee Rivers during highflow events. In addition to the interbasin transfer potential 

identified, five bighead carp have been individually collected between 1995 and 2003 in western Lake Erie (Asian 

Carp Regional Coordinating Committee, 2013). Unlike the 

St. Joseph and Milwaukee Rivers in which the movement 

of carps would progress upriver, the Maumee River may be 

susceptible to migration from both the Lake Erie side and the 

headwaters. 
6 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

The selection of the Sandusky River for data collection 

was due to the increasing concerns about Asian carp in Lake 

Erie and was made more urgent by detection of Asian carp 

eDNA in Sandusky Bay water samples (Asian Carp Regional 

Coordinating Committee, 2012). The Sandusky River has an 

impassible dam (Ballville Dam, table 1), which significantly 

shortens the river reach that would be available to carps entering the system from Lake Erie. However, removal of that dam 

has been planned, which would increase the length of the river 

accessible to migratory fish, and, therefore, increase the likelihood of suitability for Asian carp spawning and recruitment.

Methodology

In addition to publishing the data collected as part of this 

study, this report shares the methodology developed to collect 

the required field data for assessment. The ideal field data-collection methods are described in the “Target River Conditions 

and Sampling Locations” and “Measurement Procedures” 

sections, which summarize the planned approach and can be 

used by others for future studies. Field crews were briefed on 

these methods during conference calls before field-data collection and provided written instructions for their reference. Field 

crews were given flexibility to use their judgment and experience to adjust aspects of the data collection such as cross section placement and spacing to collect the most representative 

data in a safe manner. Departures from the ideal methods that 

occurred during the field data collection on the tributaries are 

described in the “Data Collection” section. 

Target River Conditions and Sampling Locations

Field procedures for hydraulic and water-quality data 

collections were developed for this study based on the spawning behavior of Asian carps, field experience from previous 

studies, and potential data needs for assessments. This section 

describes the ideal field data-collection scenario and can be 

used as a guide for others planning similar data-collection 

efforts.

Hydraulic and water-quality measurements at cross sections and along the longitudinal profile should be collected 

during conditions conducive to Asian carp spawning. Measurements should be collected following an increase in water 

level and (or) flow as that triggers spawning behavior in Asian 

carps. If possible, measurements should begin on the rising 

limb of the hydrograph for a flow event, starting at the most 

upstream sampling location and moving downstream with the 

flood wave. Water temperatures should be in the range of 18 to 

30 degrees Celsius (°C) (64 to 86°F) to match the temperature 

range during which Asian carps may spawn (Kolar and others, 

2007), although spawning is reported to have occurred in the 

Lower Volga River in Russia at temperatures in the 14 to 15°C 

range (Opuszynski and Shireman, 1994). While this simple 

temperature threshold is sufficient for this study (since the 

focus is on variations in water quality along the river), a true 

measure of the onset of spawning is not based solely on water 

temperature in the tributary, but rather on the maturation rates 

of the fish, which depend on the thermal load to which the fish 

was exposed in both the lake and tributary habitats (Kocovsky 

and others, 2012). Therefore, it is important to note that while 

water temperatures in early June may be suitable for egg 

development, fish may not spawn at these temperatures if they 

have not reached the total heat required for maturation during 

that year. 

The spacing of cross sections for collecting hydraulic 

data is dependent upon the variability of the flows and the 

bathymetry of the river. The maximum spacing should be 

such that the general hydraulics are relatively constant within 

each reach defined by the cross section. In this study, planned 

cross sections were spaced approximately 1.6 km (1 river 

mile) apart from the mouth of the river to the first impassible 

structure or to the headwater of the stream using GIS and 

aerial images. The locations of the cross sections should be 

selected to avoid bridges or other structures as these structures 

generally produce flow conditions that are uncharacteristic of 

the reach. Sharp bends where cross-channel velocities may be 

large also should be avoided. The study crews were instructed 

to use the planned cross sections as a guide for locating cross 

sections in the field, but were to use their judgment as hydrographers to identify the most representative section for each 

reach. In addition to the regular cross-section sampling locations, field teams should collect a minimum of two transects 

in low-velocity pools above dams or other low-velocity cross 

sections for evaluation of the potential for egg settlement. 

Finally, hydraulic and water-quality data must be continuously collected as the boat moves down the river between 

cross sections. These data should include, at a minimum, the 

velocity, depth, and temperature of the flow measured along 

the thalweg. 

Measurement Procedures

The measurement procedures are designed to characterize 

the velocity and water quality of the river system for spawning and egg transport. As such, even though the data collection 

should be completed during a period of high flows, pools and 

other areas of low velocity are of interest for egg-settlement 

potential. Conversely, areas of elevated turbulence and turbidity are of interest for potential spawning locations.

Hydraulic data should be collected with acoustic Doppler current profilers (ADCP) and water-quality data with 

multiparameter water-quality sondes. A differentially corrected global positioning system (dGPS) should be used to 

georeference the data collected with a horizontal resolution 

generally less than 1 meter (m). Photographs and field notes 

should be taken to document sampling conditions and general 

channel characteristics. Repeat transects should be collected 

at each cross section to provide a measurement discharge and 

assess the temporal variability of the discharge at each section 
Methodology 7

(Mueller and Wagner, 2009). Collecting eight repeat transects 

allows for estimation of the longitudinal dispersion coefficient 

(Carr and Rehmann, 2007), a parameter not computed in this 

study, but one that may be of use in future assessment models. 

A longitudinal profile of velocity and bathymetry should be 

collected along the thalweg or region of greatest flow as the 

boat moves between cross sections to provide a continuous 

trace of data through the study reach. In addition to collecting 

ADCP data along eight transects, a stationary measurement 

should be performed at each cross section for a minimum 

of 5 minutes so that a time-averaged velocity profile can be 

obtained. This velocity profile allows for calculation of the 

shear velocity, which is a critical value in determining whether 

eggs will settle out of suspension. In all cases, the ADCP 

should be configured and operated in a manner that yields 

high-quality data, minimizes lost and bad data, and maintains 

bottom track and GPS lock when possible. In general, following USGS discharge-measurement procedures for instrument 

configuration and operation (Mueller and Wagner, 2009) will 

yield adequate results, though custom configurations may be 

required to achieve the best data. Care should be taken when 

choosing the proper instrument for the expected field conditions to ensure that the highest vertical resolution is achieved 

with the lowest noise possible. 

The water-quality sonde should be used to collect temperature, specific conductance, dissolved oxygen, pH, and turbidity (when available). Although temperature is the most critical 

water-quality parameter, the specific conductance, dissolved 

oxygen, and pH provide information about the general waterquality distribution of the river and the conditions to which the 

eggs are exposed. Turbidity measures visibility in the water 

column and larger values indicate less visibility which may aid 

in successful recruitment by decreasing predation on the eggs. 

The water-quality sonde should be set to collect data continuously with a sampling period of no greater than 15 seconds. 

Sampling intervals larger than 15 seconds will result in poor 

distribution across the channel. Data should be collected 

during all ADCP transects at each cross section and continuously as the boat moves longitudinally downstream from cross 

section to cross section. The water-quality sonde is required to 

be calibrated prior to deployment following necessary protocol 

(U.S. Geological Survey, variously dated), and it is recommended that the sonde be checked periodically for drift and 

fouling during deployment to ensure the data are satisfactory. 

If one is not using a sonde with built-in or external GPS, the 

sonde clock must be synced with the clock on the computer 

operating the ADCP and dGPS to ensure that the water-quality 

data can be georeferenced with the positional data logged 

from the ADCP GPS unit. The time sync must occur prior to 

deployment.

Data Collection

Data collection for the four tributaries in this study 

utilized a range of small boats equipped with ADCPs and 

multiparameter water-quality sondes. The survey on the 

Milwaukee River utilized a single crew using a combination 

of a small Jon boat, a tethered boat, and a remote-control boat. 

The surveys on the St. Joseph, Maumee, and Sandusky Rivers 

utilized two separate crews in small manned boats working in 

unison to allow for a more efficient survey. All four surveys 

utilized Teledyne RDI ADCPs (StreamPro and 1,200 kilohertz 

Rio Grande) and YSI multiparameter sondes. In addition, 

survey crews were equipped with sub-meter accuracy dGPS 

receivers (Trimble AG132 and Hemisphere Crescent A100), 

GPS-enabled digital cameras, laser rangefinders, and navigation software (Hypack® or Fugawi®). 

The Milwaukee River data were collected over a period 

of 12 days during July–August 2010 (fig. 3). Air temperatures recorded at the General Mitchell International Airport in 

Milwaukee (National Oceanic and Atmospheric Administration, 2012) and the hydrograph for the Milwaukee River at the 

USGS streamgage at Milwaukee, Wisconsin (04087000), are 

shown in figure 3. The Milwaukee River Basin experienced 

two large storms in quick succession so sampling occurred 

during a double-peaked hydrograph (fig. 3). The largest daily 

averaged flow during the event was 121.5 cubic meters per 

second (m3/s) (4,290 cubic feet per second (ft3/s)), which is 

exceeded less than 1-percent of the time (44.5 m3/s) at that 

streamgage (U.S. Geological Survey, 2012a). The sampling 

did not proceed from upstream to downstream as planned 

(fig. 8) owing to safety concerns and access issues. The headwater reaches were deemed too dangerous for data collection 

to occur at the beginning of sampling because of swift, nonnavigable water. The distance between cross sections averaged 

approximately 1.6 km (1 mile (mi)), with a maximum distance 

of 4.5 km (2.8 mi), due to issues with limited access in a shallow reach downstream of Grafton Dam. 

The hydraulic characteristics of the lower St. Joseph 

River were surveyed over 6 days during November–December 

2010 (fig. 4). The water-quality data for the St. Joseph River 

were collected in a separate field effort (for a similar magnitude event) during September 2011 because the water temperatures on the St. Joseph River were outside of the Asian carp 

spawning temperature range when the hydraulic data were 

collected. The September 2011 event occurred just a few days 

after the temperatures in the river fell below the 18°C spawning threshold. Air temperatures recorded at the South Bend 

Regional Airport in South Bend, Indiana (National Oceanic 

and Atmospheric Administration, 2012), and the hydrographs 

for the St. Joseph River at the USGS streamgage at Niles, 

Michigan (04101500), are shown in figure 4. The largest daily 

averaged flow during the November–December 2010 event 

was 83.5 m3

/s (2,950 ft3/s), and the largest daily averaged flow 

during the September 2011 event was 84.1 m3/s (2,970 ft3/s), 

which is exceeded just less than 50 percent of the time at that 

streamgage (U.S. Geological Survey, 2012b). The distance 

between cross-section locations averaged 2.2 km (1.4 mi), 

with a maximum distance of 3.7 km (2.3 mi), to accomplish 

the data collection in a reasonable amount of time. 
8 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

June July August September October

Discharge, in cubic meters per second

2010

100

10

1

1,000

0

5

10

15

20

25

30

35

Air temperature, in degrees Celsius

EXPLANATION

Sampling period: July 21–August 12

Discharge

Air temperature

Figure 3. Air temperature measured at the General Mitchell International Airport in Milwaukee, Wisconsin, and the 

hydrograph from the Milwaukee River at Milwaukee, U.S. Geological Survey streamgage (04087000), showing the field 

sampling period of this study.

The Maumee River was sampled over a period of 5 days 

during August 2011 (fig. 5). Air temperatures recorded at the 

Toledo Express Airport in Toledo, Ohio (National Oceanic and 

Atmospheric Administration, 2012) and the hydrograph for the 

Maumee River at the USGS streamgage at Waterville, Ohio 

(04193500), are shown in figure 5. The largest daily averaged 

flow during the event was 78.2 m3/s (2,760 ft3/s), which is 

exceeded less than 30 percent of the time for the months of 

May–November at that streamgage (Straub, 2001). Figure 5 

also includes the estimated maturation date for spawning 

based on the thermal load in Lake Erie from Kocovsky and 

others (2012). The distance between cross sections averaged 2.6 km (1.6 mi), if the two rapids reaches that were not 

sampled are excluded. The two rapids reaches, which are 

10.7 km (6.7 mi) and 12.8 km (8 mi) long, were excluded from 

sampling for safety and access issues.

The Sandusky River was sampled over a period of 5 days 

during September 2012 (fig. 6). However, limited access to 

the river upstream of the Ballville Dam restricted data collection in this reach and, therefore, only data downstream of 

the Ballville Dam (September 11 and 12, 2012) were used 

in this analysis. Currently (2013), Ballville Dam is impassible by migratory fish (though at the time of this publication 

(2013) it is being considered for removal). The sampled event 

occurred following a summer of drought conditions during a 

period of very low flow (base flows near 1 m3

/s) and peaked 

at 33.3 m3/s on September 10, 2012, at the USGS streamgage 

at Fremont, Ohio (04198000) (fig. 6). The largest daily averaged flow during the event was 30.9 m3

/s (1,090 ft3/s), which 

is exceeded approximately 21 percent of the time at that 

streamgage (U.S. Geological Survey, 2012c). Figure 6 also 

includes the estimated maturation date for Asian carp spawning based on the thermal load in Lake Erie from Kocovsky 

and others (2012). Water temperature at Fremont, Ohio, during 

the survey averaged about 21°C (and air temperatures varied 

between 17 and 27°C). The average distance between sampled 

cross sections was 1.7 km (1.1 mi), with a maximum distance 

of 2.25 km (1.4 mi), and data were collected continuously 

between cross sections in the lower 20 km of the river. 
Methodology 9

June July August September October November December January Feb.

2010 2011

Sampling period:

November 30–December 5

Sampling period:

September 27–30

A

B

June July August September October November

2011

0

50

100

150

200

250

Discharge, in cubic meters per second Discharge, in cubic meters per second

0

50

100

150

200

250

300

–5

0

5

10

15

20

25

30

35

40

Air temperature, in degrees Celsius

–20

–10

0

10

20

30

40

Air temperature, in degrees Celsius

EXPLANATION

EXPLANATION

Discharge

Air temperature

Discharge

Air temperature

Figure 4. Air temperature measured at the South Bend Regional Airport in South Bend, Indiana, and the hydrographs from the 

St. Joseph River at Niles, U.S. Geological Survey streamgage (04101500), showing the two field sampling periods of this study. 

A, November 30–December 5, 2010. B, September 27–30, 2011.
10 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

100

10

1

1,000

10,000

May June July August September October

2011

Maturation date: June 23

(Kocovsky and others, 2012)

–5

0

5

10

15

20

25

30

35

40

Air temperratue, in degrees Celsius

Discharge, in cubic meters per second

EXPLANATION

Sampling period: August 25–29

Discharge

Air temperature

Figure 5. Air temperature measured at the Toledo Express Airport in Toledo, Ohio, and the hydrograph from the 

Maumee River at Waterville, U.S. Geological Survey streamgage (04193500), showing the field sampling period of 

this study. Discharge, in cubic meters per second

2012

100

10

1

1,000

Air temperature, in degrees Celsius

EXPLANATION

Sampling period: September 9–12

Discharge

Air temperature

–5

0

5

10

15

20

25

30

35

40

45

0.1 May June July August September October

Maturation date: June 23

(Kocovsky and others, 2012)

Figure 6. Air temperature measured at Toledo Metcalf Field in Toledo, Ohio, and the hydrograph from the Sandusky 

River at Fremont, Ohio, U.S. Geological Survey streamgage (04198000), showing the field sampling period of this study.
Settling Velocities and Hatch Times of Asian Carp Eggs 11

Data Processing

The ADCP data were processed using the Velocity Mapping Toolbox (Parsons and others, 2012). The ADCP data were 

processed to provide depth, discharge, depth-averaged velocity, vertical velocity, acoustic backscatter, and shear velocity, 

though not all of these parameters were used in this analysis. 

The shear velocity (u*) is a critical parameter to calculate 

when evaluating whether a particle (in this case, an Asian carp 

egg) will remain in the suspension or settle out of the water 

column. A particle will only remain in suspension when the 

turbulent vertical-velocity fluctuations in the flow overcome 

the settling velocity of the particle (Bagnold, 1966). The shear 

velocity of a flow is of the same magnitude as the maximum 

value of the turbulence intensity (Hinze, 1975), allowing one 

to define the initiation of suspension of a particle as when the 

shear velocity equals the settling velocity (van Rijn, 1984). 

Therefore, when the settling velocity of the particle exceeds 

the shear velocity, the particles (eggs) can no longer remain in 

suspension. 

Shear velocity was calculated three different ways from 

the collected data. Several methods were chosen to (1) provide 

independent estimates of the shear velocity for comparison, 

(2) determine if one method is more suitable than another for 

these assessments, (3) determine what data are necessary for 

estimation of the shear velocity (different methods have different data requirements), and (4) provide continuity in data 

through reaches where one or more methods fail to produce 

reasonable estimates. In the first method, the stationary ADCP 

profiles were averaged and fit using a logarithmic profile to 

estimate the shear velocity at each cross section (Sime and 

others, 2007). The second method utilized moving-boat ADCP 

velocity profiles collected while moving between cross sections. These profiles were referenced to the bed, normalized by 

the water column depth, averaged over 120-second intervals 

to remove noise, and fit with a logarithmic velocity profile 

to estimate the shear velocity. Normalization of the profiles 

ensures that streamwise variations in depth are accounted for 

and observations of velocity from the same relative height 

above the bed are averaged together. The third method calculates an estimate of the shear velocity (u*) from the ManningStrickler power form of Keulegan’s relation (1938) 

U u * . = 8 1( ) H ks s where k 2 5. D 1

6  50 (1)

where 

U is mean velocity (meters per second), 

H is mean depth (meters), and 

ks is the effective roughness height of the 

riverbed and is approximately equal to 

2.5D50, where D50 is the median grain size 

(meters) of the riverbed sediment. 

This approach assumes no bedforms or submerged 

vegetation are present on the bed and ks is proportional to the 

median grain size of the bed substrate. For this study, substrate information was provided by assessments made by the 

Wisconsin Department of Natural Resources, the U.S. Fish 

and Wildlife Service, consultants, and academics (St. Joseph 

River—Wesley and Duffy, 1999; Milwaukee River—Will 

Wawrzyn, Wisconsin Department of Natural Resources, written commun., 2012; Maumee River—Jim Boase, U.S. Fish 

and Wildlife Service, Habitat Assessment in the Maumee 

River, unpub. data, 2007; Sandusky River—Stantec Consulting Services, 2011; and Evans and others, 2002). Substrate 

data were used to estimate the median grain size for each 

reach within the survey area. Some adjustments to these values were required for reaches where equation 1 significantly 

underpredicted the shear velocity compared to the values 

determined from fitting (likely owing to unaccounted for bedforms, vegetation, and other roughness elements). Adjustments 

were made to the effective roughness height (ks ), guided by 

estimates of the roughness height determined in fitting velocity 

profiles collected with a stationary boat. 

The water-quality data were downloaded from the waterquality sonde data loggers and georeferenced by interpolating 

the position of the instrument from the GPS navigation record 

(high resolution >1 hertz data) at the sampling times of each 

water-quality observation. The water-quality data then were 

reviewed as time series, outliers were marked and omitted 

from analysis, and the resulting dataset was used to create a 

GIS point shapefile for each river. Of the water-quality data 

collected, the most critical parameter is water temperature. 

Water temperature determines the development rate of the 

Asian carp eggs and the time elapsed between egg laying and 

hatching into larval fish. Specific conductance, dissolved oxygen, and pH are parameters that indicate general water quality, 

and higher turbidity reduces visibility in the water column and 

may aid in successful recruitment by decreasing predation on 

the eggs. While these synoptic surveys capture only a snapshot 

in time of the water-quality distributions and the observed distributions can have temporal effects included in the data, the 

distributions allow biologists to understand the overall range 

of water-quality conditions the fish and eggs may be subject to 

during a spawning event. 

Settling Velocities and Hatch Times of 

Asian Carp Eggs

Settling velocities of fertilized eggs from silver and 

bighead carp were determined in laboratory experiments during 2010–11 at the USGS Columbia Environmental Research 

Center (Duane Chapman, U.S. Geological Survey, unpub. 

data, 2011). Four critical settling velocities were identified 

from the data based on elapsed time since fertilization. After 

the eggs are deposited in the water by the female, the egg 

membrane absorbs water and the density of the egg decreases 

in a process called water hardening. A fully water-hardened 

egg is almost neutrally buoyant, but the egg changes in density 

until approximately 18 hours after fertilization. As the density 

of the egg decreases, the settling velocity also decreases. 
12 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

Table 2 presents the settling-velocity data of Chapman (Duane 

Chapman, U.S. Geological Survey, unpub. data, 2011) for 

bighead and silver carp eggs and the average settling velocity 

used in the present analysis. The settling velocity of the eggs 

within 2 hours of fertilization is approximately 2 centimeters 

per second (cm/s). From 2 to 3 hours post fertilization, the 

settling velocity of the eggs is approximately 0.85 cm/s. From 

3 to 4 hours post fertilization, the settling velocity of the eggs 

is approximately 0.8 cm/s. From 18 to 20 hours, the settling 

velocity is approximately 0.75 cm/s. According to Chapman 

(Duane Chapman, U.S. Geological Survey, unpub. data, 2011), 

the egg diameter is relatively constant after 20 hours and 

therefore, there is likely little change in the settling velocity 

after 20 hours until the egg hatches. (As previously mentioned, 

if the shear velocity of the river falls below the settling velocity of the eggs, turbulence in the water can no longer hold 

the egg in suspension, and the eggs could settle to the riverbed where it is thought they would perish (Kolar and others, 

2007)).

Table 2. Bighead and silver carp egg-settling velocities from 

Duane Chapman (U.S. Geological Survey, unpub. data, 2011), and 

approximate average settling velocities used in the 2013 analysis.

[cm/s, centimeter per second]

Developmental 

period 

(hours post 

fertilization)

Bighead 

egg-settling 

velocity 

(cm/s)

Silver 

egg-settling 

velocity 

(cm/s)

Average 

egg-settling 

velocity 

(cm/s)

0 to 2 hours 2.12 1.9 2

2 to 3 hours .9 .79 .85

3 to 4 hours .85 .77 .8

18 to 20 hours .8 .69 .75

Hatching time varies widely with temperature (Chapman 

and George, 2011) (fig. 7). Higher temperatures drive faster 

development and earlier hatching. Figure 7 presents a compilation of hatching times available in the literature for silver and 

bighead carps. The silver carp egg-hatching time data have 

been fit to allow extrapolation over the spawning temperature 

range, and bighead carp egg-hatching times have been estimated using the silver carp empirical formula as a model along 

with the data of Chapman and George (2011). Silver carp eggs 

were observed to hatch in approximately 45 hours post fertilization at 19.6°C (Chapman and George, 2011) and in as short 

as 18.5 hours at approximately 28.5°C (Murty and others, 

1986). Bighead carp hatching times have limited observations, 

but appear to follow a similar temperature dependence with 

slightly longer (approximately 3.7 hours greater at 22.3°C) 

hatching times (Chapman and George, 2011). The estimates of 

hatching times developed in figure 7 are based on limited data 

with poor temperature control in many of the studies. While 

the accuracy of the estimates should be sufficient for the purposes of this study, the estimates of hatching times developed 

herein should be used with caution.

Spawning and Egg-Transport 

Suitability Criteria

Several hydraulic and biologic factors must be assessed 

to determine if a river is capable of supporting successful 

Asian carp spawning and recruitment. The river must be 

accessible by mature Asian carps, the river must have sufficient water-quality and hydraulic characteristics to keep the 

egg alive and in suspension until hatching, and the river must 

have suitable nursery habit for juvenile fish. While the nursery 

habitat assessment is beyond the scope of this study, the 

hydraulic and water-quality assessment is presented for each 

of the four study tributaries in the remainder of this section. 

Any tributary meeting the hydraulic qualifications for spawning would have to be assessed for nursery habitat to determine 

if successful recruitment is possible.

Of particular interest in the hydraulic assessment are the 

identification of three key pieces of information about each 

of the tributaries—likely spawning areas, potential settling 

zones, and advective traveltime. Spawning sites are critical 

and thought to be in areas of high turbulence (rock outcroppings, dam spillways, behind piers) (Kolar and others, 2007), 

probably because the additional turbulence aids in keeping the non-water-hardened eggs in suspension during that 

densest developmental stage. Datasets from field crews are 

unlikely to have thoroughly measured such flows since many 

of these turbulent areas present safety, access, and instrumentoperation issues. Therefore, for the remainder of this analysis 

the assumption is that the carp will spawn in a location with 

sufficient turbulence to keep the eggs in suspension for the 

first 2 hours of development. Potential spawning locations can 

be identified in the datasets by looking at areas with the highest observed shear velocity. In contrast, potential egg-settling 

zones can be identified by determining where the estimates of 

shear velocity from each river fall below the settling velocities 

in table 2. 
Results 13

15

25

35

45

55

65

75

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Time to hatching, in hours post fertilization

Temperature, in degrees Celsius

EXPLANATION

Silver carp

Bighead carp

Murty and others (1986) 

Ahmed and others (1982)

Alikunhi and others (1963)

Chapman and George (2011)

Bardach and others (1972)

Tsuchiya (1980) (silver)

Tsuchiya (1980) (bighead)

Tsuchiya (1980) (grass)

Figure 7. Observations of hatching times for silver and bighead carps from a range of studies and empirical estimates over a 

range of temperatures.

Although a river may have sufficient flow to keep eggs 

in suspension, the river also must have sufficient length to 

allow eggs to hatch before reaching the lake in order to be 

suitable for recruitment. Therefore, an estimate of traveltime 

is required for this assessment. Cumulative traveltime for the 

peak of an egg distribution can be estimated from the field data 

by computing the 120-second mean depth-averaged velocity 

from longitudinal ADCP data. Dividing the streamwise distance between observations by the mean velocity at each point 

and then summing the traveltime over the individual reaches 

yields the time required to travel from the top of the sampled 

reach to the mouth of the river. The traveltime of the peak concentration of eggs does not take into account how the plume 

of eggs would spread out due to dispersion. Therefore, the 

leading edge and trailing edge traveltimes are estimated using 

empirical equations and are included to represent the range of 

traveltimes for the plume. The leading edge and trailing edge 

(to 10 percent of peak concentration) traveltimes are estimated 

based on empirical relations developed by Jobson (1996). 

Traveltimes can be compared to hatching times documented 

in Chapman and George (2011) to determine if the eggs will 

hatch prior to reaching the river mouth or another settling zone 

where they likely will settle out and perish. 

Results

The four study tributaries were analyzed for spawning suitability based on the criteria outlined in the previous 

section—likely spawning areas, potential settling zones, and 

advective traveltime. This section presents the results from 

each of these case studies. In addition, this section presents a 

method for estimating the minimum velocity needed to keep 

water-hardened eggs in suspension based on the flow depth 

and substrate type. 

Tributary Case Studies

Milwaukee River

The lower 100 km of the Milwaukee River generally is 

fast flowing and shallow, except for backwater areas behind 

the largest of the eight dams that occupied this reach at the 

time of the survey (two dams have since been removed) 

(fig. 8). Mean flow velocities observed upstream of Grafton 

Dam were approximately 45 cm/s, while those downstream of 

the dam were significantly higher, averaging approximately 

70 cm/s, except within the estuary downstream of the former 

North Avenue Dam where the velocity abruptly decreased and 

pulsed in response to the lake seiche (fig. 9A). The highest 

velocities observed were downstream of dams, and the lowest 

velocities observed were in the impoundments upstream of the 

dams. The Grafton, Thiensville, and Estabrook Dams had the 

greatest impact on the flow both upstream and downstream of 

the dams. Vertical velocities measured with the ADCP, while 

noisy, were markedly smaller upstream of the Thiensville, 

Grafton, and Newburg Dams. The fluctuations in the vertical 

velocities are an indication of the amount of turbulence in the 

river.
14 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

EXPLANATION

pH, in standard units

Dam with name–red dams have been removed

8.03 to 8.12

8.13 to 8.21

8.22 to 8.30

8.31 to 8.39

8.40 to 8.48

8.49 to 8.57

Depth, in meters

0.2 to 1.0

1.1 to 2.0

2.1 to 3.0

3.1 to 4.0

4.1 to 5.0

5.1 to 6.0

6.1 to 7.0

7.1 to 8.0

8.1 to 9.0

9.1 to 10.0

Specific conductance, in millisiemens per centimeter

0.465 to 0.500

0.501 to 0.550

0.551 to 0.600

0.601 to 0.650

0.651 to 0.700

0.701 to 0.750

0.751 to 0.800

Temperature, in degrees Celsius

21.2 to 22.2

22.3 to 23.2

23.3 to 24.3

24.4 to 25.3

25.4 to 26.4

26.5 to 27.4

27.5 to 28.4

28.5 to 29.5

Dissolved oxygen, in milligrams per liter

6.5 to 7.0

7.1 to 8.0

8.1 to 9.0

9.1 to 10.0

10.1 to 11.0

11.1 to 12.0

Depth-averaged vertical velocity, in centimeters per second

0.1 to 2.0

2.1 to 4.0

4.1 to 6.0

6.1 to 10.0

–24.5 to –6.0

–5.9 to –4.0

–3.9 to –2.0

–1.9 to 0.0

Depth-averaged velocity, in centimeters per second

101 to 125

126 to 150

151 to 175

176 to 200

0 to 25

26 to 50

51 to 75

76 to 100

Survey date–July 21 to August 12, 2010

21

22

27

28

29

30

6

8

9

10

11

12

Shear velocity, in centimeters per second

0.76 to 0.80

0.81 to 0.85

0.86 to 2.00

2.01 to 4.00

4.01 to 6.00

6.01 to 10.00

10.01 to 14.00

Settling possible

0

0

10

10

20 KILOMETERS

20 MILES

Flow

Lake

Michigan

West 

Bend

Grafton

Newburg

(removed 

2012)

Thiensville

Kletzsch Estabrook

North Avenue

(removed 1997)

Figure 8. Hydraulic and water-quality data for the Milwaukee River, Wisconsin, July 21–August 12, 2010.
Results 15

0

0 10 20 30 40 50 60 70 80 90 100

Time to advect to mouth, in hours

Distance from mouth, in kilometers

Peak

Leading edge

Trailing edge (10 percent)

Mean velocity, 

in centimeters per second 

Potential egg-settling zones

Reach traveltime, in hours

0.1

1

10

Shear velocity, in centimeters per second

25

50

75

100

125

150

110

0

20

40

60

80

100

120

140

160

180

Freshwater

estuary

Newburg Dam

(Removed 2012)

North Avenue

Dam 

(Removed

1997)

West Bend Dam

Estabrook Dam Estabrook Dam

Kletzsch Dam

Thiensville 

Dam

Lime Kiln Dam (Removed 2011)Grafton Dam (Bridge Street)

Water-hardened

eggs begin to settle

Non-waterhardened

eggs begin

to settle 

Freshwater

estuary

Egg-settling threshold (just after fertilization)

Egg-settling threshold (2 to 3 hours post fertilization)

Egg-settling threshold (3 to 4 hours post fertilization)

Egg-settling threshold (18–20 hours post fertilization)

u* (Stationary boat, profile fitting)

u* (Moving boat, profile fitting)

u* (Moving boat, Keulegan's relation (1938))

EXPLANATION

All Asian carp 

eggs begin 

to settle

B

C

A

29

24

20

43

35

32

(Removed 1997) 

North Avenue Dam Kletzsch DamThiens

Dam

ville 

Lime Kiln Dam (Removed 2011)Grafton Dam (Bridge Street)West Bend Dam

Newburg Dam

(Removed 2012)

Figure 9. A, Mean velocity, B, estimated advection time, and C, shear velocity for the Milwaukee River, Wisconsin, July 21–

August 12, 2010.
16 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

Water-quality distributions within the Milwaukee River 

were dominated by temporal (diurnal) changes and otherwise 

showed little variation (fig. 8). Observed water temperatures 

upstream of the river mouth ranged from 23 to 29°C, with a 

majority of the variation (up to 5°C) attributable to diurnal 

variations. Dissolved oxygen was relatively uniform with 

values from 7 to 9 milligrams per liter (mg/L) for most of the 

river, except for several reaches upstream of Grafton Dam 

where diurnal changes in water temperature are correlated 

with high dissolved oxygen (9 to 12 mg/L). The diurnal 

change in dissolved oxygen in these reaches may be indicative of oxygen production by aquatic vegetation during peak 

solar-radiation periods in the midday and afternoon, which 

also would lead to the observed increase in water temperatures. Survey crew notes and photos documented these reaches 

as having very abundant aquatic vegetation across the width 

of the channel. Areas with higher dissolved oxygen also 

exhibited higher values of pH (consistent with high rates of 

photosynthesis from vegetation) and otherwise showed little 

variation along the river. Specific conductance showed little 

variation in the river when accounting for temporal variation. 

The lower Milwaukee River includes several zones 

that may allow settlement of Asian carp eggs; however, the 

potential settlement reaches are short and traveltimes between 

reaches appear to be sufficient for egg development to hatching prior to reaching these settlement zones (fig. 9B). Two 

potential egg-settling zones were identified in which the shear 

velocity was lower than the settling velocity of the eggs. A 

2-km reach above Grafton Dam was determined to have a sufficiently low shear velocity to settle out water-hardened eggs. 

The second settling zone identified is the estuary where the 

Milwaukee River meets Lake Michigan. The estuary settling 

zone is approximately 5 km long. There also were several 

pools identified to have low shear velocities (fig. 9C), mostly 

areas upstream of dams. It is important to note that Newburg 

Dam, which is the source of one of these low shear velocity 

pools, was removed in 2012 and that likely changed the flow 

characteristics in this area to eliminate the pool. Advective 

traveltimes between the primary settling zones identified in 

figure 9B are 24 and 35 hours, respectively, for the peak of 

the egg distribution. The estimated times to hatching for silver 

and bighead carps at a water temperature of 26.0°C (mean 

water temperature during the survey) are approximately 20 

and 23 hours, respectively. These traveltimes indicate that at 

the observed temperatures these reaches are sufficiently long 

to allow both silver and bighead carp eggs to develop to the 

hatching phase before reaching a settling zone. 

The highest observed turbulence, as indicated by high 

shear velocities, were observed in the lower 50 km of the 

Milwaukee River, specifically just downstream of the Grafton, 

Thiensville, and Estabrook Dams. Additionally, the data indicate high shear velocities downstream of the West Bend Dam. 

The high-velocity, high-gradient portion of the lower 50 km 

of the Milwaukee River and areas immediately downstream of 

the previously mentioned dams may present attractive spawning conditions for Asian carps. Grafton Dam currently (2013) 

has no fish ladder and it is considered the terminal point for 

upstream migration of most fish species (Will Wawrzyn, 

Senior Fisheries Biologist, Wisconsin Department of Natural 

Resources, written commun., 2012). The impedance of the 

Grafton Dam combined with the high turbulence downstream 

of the dam make this location a favorable spawning location 

for Asian carps. 

St. Joseph River

Five dams located along the lower 100 km of the 

St. Joseph River heavily influence the hydraulics of the river 

(fig. 10). Mean velocities during the surveyed event ranged 

from 50 to 150 cm/s downstream of dams and within the 

free-flowing lower 40 km of the river, to less than 25 cm/s 

within the backwater pools upstream of the Berrien Springs, 

Buchannan, and South Bend Dams and within the estuary 

at the river mouth (fig. 11A). Like the observations from the 

Milwaukee River, a significant decrease in the vertical velocity was observed in the backwater areas behind the dams. 

Impoundments provided the greatest depths (3 to 8 m) while 

the remainder of the river exhibited depths that averaged from 

1 to 3 m. 

Variability in the water-quality distributions in the 

St. Joseph River appear to be influenced by a combination of 

anthropogenic sources and tributary inflows (fig. 10). Temperature variation within the lower 100 km is low (<1°C) 

accounting for temporal variations. Signatures of both 

anthropogenic and tributary inflows can be seen near river 

kilometer 66 where the Niles Wastewater Treatment Plant 

effluent and Dowagiac River both enter the river, slightly 

raising the local water temperature (fig. 10). In contrast, the 

cooler water observed above the South Bend Dam may be 

the effect of a local anomaly owing to inflows from Bowman 

Creek. While temperatures were low (approximately 16°C 

during this survey), the mean water temperature at the USGS 

streamgage at Niles, Mich. (04101500), was 26.5°C for the 

month of July based on data from July 2011 and July 2012. 

Dissolved oxygen, pH, and turbidity all decreased in impoundments and increased downstream of the dams (fig. 10). In 

contrast, the specific conductance increased slightly upstream 

of the Berrien Springs and Buchanan Dams, within the lower 

30 km of the river, and just downstream of the South Bend 

Wastewater Treatment plant and Judy Creek inflow near river 

kilometer 81. The cause of the increase in specific conductance upstream of the dams is unclear, but the higher specific 

conductance from river kilometer 30 to the mouth may be 

owing to contribution from Lemon Creek, which also appears 

to have increased the turbidity concentrations in the St. Joseph 

River near the confluence (fig. 10). 
Results 17

0

0

10

10

20 KILOMETERS

20 MILES

EXPLANATION

pH, in standard units

Turbidity, in nephelometric turbidity units (NTU)

Dam with name

7.86 to 7.92

7.93 to 7.97

7.98 to 8.03

8.04 to 8.08

2 to 3

4 to 5

6

7 to 8

8.09 to 8.14

8.15 to 8.19

9 to 12

13 to 20

21 to 35

36 to 118

Depth, in meters

0.4 to 1.0

1.1 to 2.0

2.1 to 3.0

3.1 to 4.0

4.1 to 5.0

5.1 to 6.0

6.1 to 7.0

7.1 to 8.0

8.1 to 9.0

Specific conductance, in millisiemens per centimeter

0.521 to 0.537

0.538 to 0.554

0.555 to 0.570

0.571 to 0.586

0.587 to 0.603

0.604 to 0.619

Temperature, in degrees Celsius

14.8 to 15.1

15.2 to 15.3

15.4 to 15.6

15.7 to 15.9

16.0 to 16.2

16.3 to 16.4

Dissolved oxygen, in milligrams per liter

8.41 to 8.54

8.55 to 8.67

8.68 to 8.79

8.80 to 8.92

8.93 to 9.05

9.06 to 9.18

9.19 to 9.30

9.31 to 9.43

Depth-averaged vertical velocity, in centimeters per second

– –

–

3.9 to 2.0

1.9 to 0.0

0.1 to 2.0

2.1 to 4.0

–14.6 to 10.0

9.9 to 8.0

7.9 to 6.0

5.9 to 4.0

–

– –

– –

– –

Depth-averaged velocity, in centimeters per second

101 to 125

126 to 150

1 to 25

26 to 50

51 to 75

76 to 100

Water-quality data–

Sept. 27–30, 2011

27

28

29

30

Hydraulic data–

Nov. 30–Dec. 5, 2010

30

1

2

3

4

5

Shear velocity, in centimeters per second

0.15 to 0.75

0.76 to 0.80

0.81 to 0.85

0.86 to 2.00

2.01 to 4.00

4.01 to 6.00

6.01 to 8.00

8.01 to 10.00

Survey date:

Settling possible

Flow

Lake

Michigan

Ball 

Band

South

Bend

French Paper Company

Barrien Springs

Buchanan

Lemon Creek

inflow

Niles wastewater

treatment plant

Dowagiac

River inflow

Bowman Creek

inflow

Judy Creek

inflow

South Bend

wastewater

treatment plant

Figure 10. Hydraulic and water-quality data for the St. Joseph River, Michigan and Indiana, November 30–December 5, 2010 

(hydraulic data), and September 27–30, 2011 (water-quality data).
18 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

0 10 20 30 40 50 60 70 80 90 100

Time to advect to mouth, in hours

Distance from mouth, in kilometers

Peak

Leading 

edge

Trailing edge (10 percent)

0

20

40

60

80

100

120

140

Mean velocity, 

in centimeters per second 

Potential egg-settling zones

Shear velocity, in centimeters per second

Non-water-hardened

eggs begin to settle

Water-hardened

eggs begin to settle

All Asian carp eggs

begin to settle

0

10

20

30

40

50

60

70

80

90

100

110

160

Berrien Springs 

Dam

Berrien Springs Dam

Buchanan Dam

Buchanan Dam

French Paper 

Company 

Dam (Niles)

French Paper Company 

Dam (Niles)

South Bend 

Dam

South Bend

Dam

Ball Band Dam (Mishawaka) Ball Band Dam (Mishawaka)

0.1

1

10

Egg-settling threshold (just after fertilization)

Egg-settling threshold (2 to 3 hours post

 fertilization)

Egg-settling threshold (3 to 4 hours post

 fertilization)

Egg-settling threshold (18–20 hours post

 fertilization)

u* (Stationary boat, profile fitting)

u* (Moving boat, profile fitting)

u* (Moving boat, Keulegan's relation (1938))

EXPLANATION

20 Reach traveltime, in hours

16

14.5

5.1

28.8

4.5

24.3

4.4

21.7

B

C

A

Figure 11. A, Mean velocity, B, estimated advection time, and C, shear velocity for the St. Joseph River, Michigan and Indiana, 

November 30–December 5, 2010 (hydraulic data), and September 27–30, 2011 (water-quality data).
Results 19

Dams on the St. Joseph River create well-defined settling zones due to their significant deceleration of the flow 

(fig. 11A). Three potential egg-settling zones were identified 

from the shear velocity data. The Buchanan Dam forms an 

approximately 4 km long settling zone within the impoundment where some settling of eggs is likely to occur. The 

Berrien Springs Dam forms an approximately 9 km long 

settling zone where significant settling of water-hardened 

eggs is likely to occur. There also were pool areas behind the 

French Paper Company and South Bend Dams identified to 

have low shear velocities (fig. 11) where some egg settlement 

may occur, particularly of the more dense non-water-hardened 

eggs. Settling also is possible within about 2 km of the river 

mouth. In contrast, the highest shear velocities were observed 

within the lower 38 km of the river and downstream of the 

dams. The dam at South Bend appeared to generate the highest 

shear velocity (and turbulence) downstream of its spillway. 

The turbulence downstream of each of the major dams on the 

lower St. Joseph River may present attractive spawning conditions for Asian carps. 

The peak transport time from the top of the sampling 

reach to the first potential settling zone upstream of Buchanan 

Dam is approximately 24 hours with leading and trailing edge 

transport times of 22 and 29 hours, respectively (fig. 11B). 

This length of time like would likely be sufficient under typical July water temperatures (26.5°C) for Asian carp eggs to 

develop to hatching (approximately 19 hours for silver carp 

and 22 hours for bighead carp at 26.5°C). The peak transport 

time between the Buchanan and Berrien Springs Dams is 

4.5 hours with leading and trailing edge transport times of 4 

and 5 hours, respectively. Eggs spawned in the reach between 

these two dams would be likely to settle to the bottom of the 

river and not hatch. The peak transport time from below Berrien Springs Dam to the settling zone where the St. Joseph 

River meets Lake Michigan is approximately 16 hours with 

leading and trailing edge transport times of 15 and 20 hours, 

respectively. It is likely that successful hatching may occur 

within this reach for peak summertime temperatures and lower 

flow rate events; however, based on the variability in hatching times observed in figure 7, only a fraction of the eggs may 

hatch before reaching the lake. 

Maumee River

The lower 100 km of the Maumee River can be divided 

into three primary sections: (1) the upper reach between Independence and Providence Dams dominated by steady, slow 

flows; (2) the middle swift-water reach between Providence 

Dam and Perrysburg, Ohio, dominated by rapids; and (3) the 

lower freshwater estuary starting about 24 km upstream of the 

mouth and dominated by highly variable flows due to backwater effects and lake seiches (fig. 12). The surveyed reach 

between Independence and Providence Dams exhibited little 

flow variability, had a gradual decrease in the flow velocity in 

the downstream direction (mean velocities ranged from 15 to 

30 cm/s, fig. 13A), and had depths ranging from 2 to 5 m. The 

rapids section below Providence Dam generally was inaccessible by boat, resulting in little measured data. These rapids 

are comprised of sections of swift water with velocities greater 

than 1 m/s and short pools between bedrock and cobble riffles 

with velocities less than 20 cm/s. Downstream of Perrysburg, 

Ohio, the Maumee River is in backwater and becomes a freshwater estuary with highly variable velocities (mean velocities 

ranging from 0.25 to 30 cm/s), reversing flows, and depths up 

to 10 m. The highly variable velocities in this 24 km long estuary are due to periodic seiches on Lake Erie and wind-driven 

currents within the estuary and nearshore Lake Erie. The 

highly variable hydrodynamics observed within the Maumee 

River estuary are consistent with prior studies (Miller, 1968; 

Herdendorf and others, 1977; Kunkle and Wordelman, 1978). 

The Maumee River exhibited less temporal variation in 

water quality than the other rivers in the study and several 

aspects of this dataset warrant further discussion (fig. 12). The 

mean water temperature for the lower 100 km of the Maumee 

River during the survey was approximately 26°C with slightly 

higher temperatures observed upstream of Providence Dam 

and the lowest temperatures just downstream of the swiftwater rapids. Diurnal changes in water temperature ranged 

from 1 to 3°C. Consistent with other Great Lakes tributaries, the specific conductance in the river was significantly 

higher than Lake Erie water and concentrations dropped upon 

entering the estuary. Contrary to intuition, dissolved oxygen 

was higher in the pool upstream of Providence Dam (approximately 12 mg/L) as compared to the sections downstream of 

the rapids (6–10 mg/L) and within the estuary (5–10 mg/L). 

Values of pH were uniform (8.5–8.7) for most of the river, 

with slightly lower values near Lake Erie (8.1–8.4) and higher 

values just downstream of the town of Napoleon, Ohio (river 

kilometer 70), where pH values approached 9.4. An elevated 

temperature (near 30°C), a 15 percent decrease in specific 

conductance, and a large rise in dissolved oxygen (75 percent) also occurred just downstream of the town of Napoleon. 

Several outfalls to the Maumee River are present downstream 

of Napoleon including one from the Napoleon Waste Water 

Treatment Plant and nine outfalls from the Campbell’s Soup 

plant. 
20 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

Rapids

U.S. Geological Survey streamgage 04193500, 

Maumee River at Waterville, Ohio

EXPLANATION

pH, in standard units

Dam with name

8.1 to 8.2

8.3 to 8.4

8.5 to 8.6

8.7 to 8.8

8.9 to 9.0

9.1 to 9.2

9.3 to 9.4

Depth, in meters

0.8 to 1.0

1.1 to 2.0

2.1 to 3.0

3.1 to 4.0

4.1 to 5.0

5.1 to 6.0

6.1 to 7.0

7.1 to 8.0

8.1 to 9.0

9.1 to 10.0

10.1 to 11.0

Specific conductance, in millisiemens per centimeter

0.467 to 0.480

0.481 to 0.510

0.511 to 0.540

0.541 to 0.570

0.571 to 0.600

0.601 to 0.630

Temperature, in degrees Celsius

23.3 to 24.0

24.1 to 25.0

25.1 to 26.0

26.1 to 27.0

27.1 to 28.0

28.1 to 29.0

29.1 to 30.0

Dissolved oxygen, in milligrams per liter

5.1 to 6.0

6.1 to 8.0

8.1 to 10.0

10.1 to 12.0

12.1 to 14.0

14.1 to 16.0

16.1 to 18.0

18.1 to 20.0

20.1 to 22.0

22.1 to 24.0

24.1 to 26.0

Depth-averaged vertical velocity, in centimeters per second

–1.9 to 0.0 6.1 to 8.0

0.1 to 2.0

2.1 to 4.0

4.1 to 6.0

–9.5 to 8.0

7.9 to 6.0

5.9 to 4.0

3.9 to 2.0

–

– –

– –

– –

Depth-averaged velocity, in centimeters per second

23 to 31

32 to 52

53 to 87

88 to 150

0.25 to 6.4

6.5 to 12

12 to 16

17 to 22

Survey date, August 25–29, 2011

25

26

27

28

29

Shear velocity, in centimeters per second

0.40 to 0.75

0.76 to 0.80

0.81 to 0.85

0.86 to 2.00

2.01 to 3.00

3.01 to 3.30

Settling possible

Flow

Lake

Erie

Independence

Providence/

Grand Rapids

Napoleon

Perrysburg

Campbell’s

Soup plant

0

0

25 KILOMETERS

25 MILES

Figure 12. Hydraulic and water-quality data for the Maumee River, Ohio, August 25–29, 2011.
Results 21

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90 100

Time to advect to mouth, in hours

Distance from mouth, in kilometers

Peak

Leading edge

Trailing edge (10 percent)

0

20

40

60

80

100

120

140

Mean velocity, 

in centimeters per second 

Freshwater estuary

Freshwater estuary

Rapids Rapids

Potential egg-settling zones

0.01

0.1

1

10

Shear velocity, in centimeters per second

 

Providence Dam 

(Grand Rapids)

Providence Dam 

(Grand Rapids)

Independence 

Dam (Defiance) Independence Dam (Defiance)

Non-water-hardened

eggs begin to settle

Water-hardened

eggs begin to settle

All Asian carp eggs

begin to settle

Seiche

slack

water

Egg-settling threshold (just after fertilization)

Egg-settling threshold (2 to 3 hours post fertilization)

Egg-settling threshold (3 to 4 hours post fertilization)

Egg-settling threshold (18–20 hours post fertilization)

u* (Stationary boat, profile fitting)

u* (Moving boat, profile fitting)

u* (Moving boat, Keulegan's relation (1938))

EXPLANATION

USGS Streamgage (04193500)

Computed velocity range at U.S. Geological Survey 

streamgage (04193500) at Waterville, 

following Kocovsky and others (2012)

Reach traveltime, in hours

B

C

A

27

26

23

47

37

35

Figure 13. A, Mean velocity, B, estimated advection time, and C, shear velocity for the Maumee River, Ohio, 

August 25–29, 2011.
22 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

The hydraulics in the lower Maumee River dictate a 

largely varying capacity for Asian carp egg transport (fig. 13). 

Several long reaches are capable of egg transport, including 

the 30 km rapids section, and two large potential settling zones 

were identified. One of the settling zones is located upstream 

of the Providence Dam in Grand Rapids, 52 km upstream 

from the mouth and extends to approximately 71 km above the 

mouth. All three shear velocity calculation methods identified 

this area as potentially settling out eggs. While the Providence 

Dam does not decelerate the flow to the extent that was seen 

for the dams on the St. Joseph River, the low velocities in the 

pool between the Independence and Providence Dams result in 

potential settling well upstream of the dam. A second settling 

zone is located in the estuary upstream of the confluence with 

Lake Erie. This settling zone is approximately 22 km long 

and spans nearly the entire 24 km long extent of the estuary. 

Shear velocity calculation in this area was complicated by 

flow fluctuations created by seiche-driven pulses in water level 

and discharge within the estuary. The inconsistency in velocity data within the estuary made fitting the velocity profile 

more uncertain and led to a larger range of estimated shear 

velocities.

In spite of having large settling zones within the lower 

Maumee River, the advective transport times upstream of 

these settling zones are sufficiently long to allow Asian carp 

eggs to develop to hatching at the high temperatures in the 

Maumee River in late summer (fig. 13B). With a mean water 

temperature of 26°C, silver and bighead carps require approximately 20 and 23 hours, respectively, to hatch (fig. 7). The 

transport time for the peak concentration of an egg distribution 

is approximately 24 hours from the top of the study reach to 

the upstream end of the first identified settling zone behind 

the Providence Dam. The transport time for the leading and 

trailing edges is 22 and 30 hours, respectively. However, if 

the traveltime curve is extended with the same slope upstream 

of the study reach another 9 km to the Independence Dam 

at Defiance, Ohio, the peak transport time is 37 hours with 

leading and trailing edge transport times of 35 and 47 hours, 

respectively. Those traveltimes are sufficient for hatching, 

and the extension is reasonable considering there are no large 

obstructions in the channel upstream from where sampling 

began. The peak transport time between the Providence Dam 

and the estuary settling zone is estimated to be 26 hours with 

leading and trailing edge transport times of 23 and 27 hours, 

respectively. It is likely that some eggs would have sufficient 

development time to hatch in the reach of the Maumee River 

between the dam and the estuary. 

Data collection was limited in the rapids reach because 

of safety concerns; therefore, some velocities in this reach 

were estimated using bed slope. The rapids section just 

downstream of the Providence Dam has an approximate mean 

slope of 5.7 x 10−4, and the rapids reach, including the USGS 

streamgage at Waterville, Ohio (04193500), has an approximate mean slope of 9.5 x 10−4. Utilizing this information along 

with estimates of Manning’s roughness coefficient (Chow, 

1959) and hydraulic geometry within the reaches, Manning’s 

equation was used to obtain approximate mean velocities 

throughout the rapids reaches. In this analysis, a weighted 

mean was applied to account for the percentage of riffles and 

pools (determined using aerial imagery) within each reach. 

Pools were given a lower velocity (0.15 cm/s) compared to 

the riffles (determined using Manning’s equation). The final 

estimates of traveltimes through the rapids reaches were 

computed using a mean velocity in the upper, pool-dominated 

rapids reach of 28 cm/s and a mean velocity of 1.0 m/s in the 

lower, steeper rapids reach. 

Kocovsky and others (2012) discussed the possibility of 

the Maumee River among others for Asian carp spawning. 

Citing the difficulty in obtaining data on the shear velocity 

in a river, linear (streamwise) velocity was used to determine 

whether eggs were likely to stay suspended. The mean velocity for the whole of the Maumee River was estimated from 

the discharge data at the USGS streamflow-gaging station at 

Waterville, Ohio (04193500), which is located in the lower, 

bedrock-riffle dominated rapids reach. This velocity estimated 

from the daily discharge data at the gage then was compared 

to a value of 70 cm/s, an estimate often cited as the velocity 

needed to keep the eggs in suspension. Kocovsky and others (2012) concluded that there was sufficient flow to keep 

eggs suspended based on this comparison. This approach for 

a tributary spawning assessment was proposed for rivers in 

which detailed hydraulic data are not available. However, 

while their conclusion that the Maumee River could support successful spawning is upheld by the current study, their 

approach is complicated by the fact, as figure 13 shows, that 

the gage is located in a section of rapids and therefore, is not 

representative of the velocity over the majority of the lower 

Maumee River.

Observations of high shear velocities in the Maumee 

River are limited for this study between the rapids reaches 

and the high flows downstream of dam spillways; however, 

the lower Maumee River should possess suitable spawning 

grounds for Asian carps (fig. 13). The most likely spawning 

grounds for the reach above Providence Dam is at the spillway 

of the Independence Dam, as this study documented low-turbulence flow in the remainder of the reach. The rapids below 

the Providence Dam are likely spawning grounds due to the 

high velocities, bedrock outcroppings, and turbulence generated by the flow over the Providence Dam spillway. In both 

reaches, if the carp spawn just downstream of either of the 

dams, there appears to be sufficient reach length and velocity 

downstream for the eggs to drift and hatch before settling out 

of the water column. 
Results 23

Sandusky River

The lower Sandusky River below Ballville Dam can be 

divided into five primary reaches based on channel and flow 

characteristics (Stantec Consulting Services, 2011; Evans and 

others, 2002) (fig. 14). The upper three reaches have shallow 

depths (<1 m, on average) and were not measured during this 

study owing to access and safety issues, but their characteristics are documented in the literature (Stantec Consulting 

Services, 2011; Evans and others, 2002). Extending about 

0.6 km downstream of Ballville Dam is a relatively high gradient (6.2 x 10-3 meters per meter (m/m)) bedrock reach with 

swift (approximately 80 cm/s mean velocity for the discharge 

in this study), shallow flow. The dam spillway, bedrock 

substrate, and swift flows generate significant turbulence in 

this reach. Extending approximately 1.7 km downstream of 

the bedrock reach is the “habitat” reach (Stantec Consulting 

Services, 2011) with prevalent gravel and cobble substrate, a 

slope of 2.9 x 10-3 m/m, and mean velocities of about 60 cm/s 

at the study discharge. The third reach, called the “Levee” 

reach, extends 1.1 km downstream of the habitat reach and is 

bounded by floodwalls. The substrate varies substantially from 

bedrock to clay, with a predominance of sand and fine gravel 

(Stantec Consulting Services, 2011). The slope of this reach 

is 8.33 x 10-4 m/m, and approximate mean flow velocities are 

50 cm/s for the study discharge. The fourth reach, extending 

2.2 km downstream of the Levee reach, is the lake-affected 

transitional reach. Within this reach, the backwater from the 

lake begins affecting the hydrodynamics, and the substrate 

transitions to fine silts and clays. The slope is approximately 

3.9 x 10-4 m/m in this reach with a mean velocity of less 

than 40 cm/s for the study discharge. The final reach of the 

lower Sandusky River is the estuary reach extending 20 km 

from the end of the transitional reach to Muddy Creek Bay 

(fig. 14). Dominated by backwater from Lake Erie, this reach 

has a mean velocity of less than 20 cm/s, and flows become 

highly variable with flow reversals due to lake-seiche activity and wind events near the bay. Depths in this reach vary 

significantly from 1 to 6 m. The lower portion of this reach 

has numerous backwater areas and resembles a marsh ecosystem (Stantec Consulting Services, 2011). This reach is the 

most likely settling zone, so measurements in this study were 

concentrated in this 20 km long estuary reach.

The lower Sandusky River exhibits significant variability in water quality as the water body transitions from 

river to estuary (fig. 14). The mean water temperature for the 

lower 25 km of the Sandusky River during the survey was 

approximately 22°C with diurnal changes in water temperature of 3°C. Higher temperatures of some backwater areas and 

tributary inflows produced anomalies in the water-temperature 

data collected in the main channel. Unlike other Great Lakes 

tributaries in the study, the specific conductance in the river 

increased in the estuary and approached a maximum for the 

survey at Muddy Creek Bay (an intermediate bay between 

the mouth of the river and Sandusky Bay). Dissolved oxygen 

was highest downstream of the Ballville Dam (approximately 

9 mg/L at the most upstream point in the survey) and dropped 

steadily within the estuary (6–8 mg/L). Diurnal variations 

of dissolved oxygen appear to be about 1 to 2 mg/L, with 

the lowest values occurring in the morning (likely owing to 

consumption at night caused by respiration and production 

during the day by aquatic plants and algae). Values of pH 

were uniform (7.7–8.2) for most of the river. Finally, turbidity 

was highest at the top of the survey reach closest to Ballville 

Dam (77 nephelometric turbidity units (NTU)) and decreased 

steadily into the estuary (down to 33 NTU). However, midway 

through the estuary, the survey crews on September 12, 2012, 

observed higher turbidity values in the estuary (60–70 NTU), 

but this may be a diurnal effect or was caused by resampling 

of the slug of high turbidity water measured close to the dam 

on day 1 (traveltime is about 20–25 hours for this reach and 

the time between sampling ending on September 11, 2012, 

and resuming on September 12, 2012, was about 15 hours). 

Periodic fluctuations in turbidity are seen in the data near the 

mouth of the river at Muddy Creek Bay and may be due to 

turbulence and resuspension of sediment arising from seicheinduced flow reversals and wind-driven wave action. Overall, 

the turbidity for the lower Sandusky River was considerably 

higher than the turbidity measured on the St. Joseph River. 

The higher turbidity could contribute to more recruitment success in the lower Sandusky River. 

Unlike the Maumee River in which nearly all of the 

24-km long estuary reach is conducive to egg settling, the 

upper 9 km of the 20 km long estuary reach of the lower Sandusky River appears capable of transporting water-hardened 

Asian carp eggs (fig. 15). The primary settling zone observed 

in the current study was in the lower 11 km of the Sandusky 

River. Within this settling zone, the shear velocity was low 

enough to allow all Asian carp eggs to settle (water-hardened 

and non-water-hardened). Upstream of this settling zone, some 

settling of non-water-hardened eggs may occur, and these data 

indicate some settling of water-hardened eggs may occur near 

the top of the estuary reach. The unmeasured reach below 

Ballville Dam appears to be suitable for Asian carp spawning, 

and velocities are high enough to maintain non-water-hardened eggs in suspension. While the Sandusky and Maumee 

Rivers have similar length estuary reaches, the Sandusky 

River appears to be less affected by lake-seiche activity as 

flow reversals were only apparent near the mouth of the river 

at Muddy Creek Bay. This lack of flow variability in the upper 

portion of the Sandusky River estuary reach allows the flow 

to transport eggs farther into the estuary reach as compared to 

the Maumee River estuary. The likely cause for the lower flow 

variability in the Sandusky River is the dampening effect of 

Sandusky and Muddy Creek Bays on the lake-seiche activity. 

These bays are shallow with depths generally less than 1.6 m 

deep (Herdendorf and Lindsay, 1975). The shallow waters and 

large, 30 km length of these bays may allow for significant 

dampening of lake-induced fluctuations prior to reaching the 

mouth of the Sandusky River.
24 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

EXPLANATION

pH, in standard units

Turbidity, in nephelometric turbidity units (NTU)

Dam with name

7.70 to 7.77

7.78 to 7.84

7.85 to 7.90

7.91 to 7.97

33 to 39

40 to 44

45 t0 50

51 to 55

7.98 to 8.04

8.05 to 8.11

8.12 to 8.17

8.18 to 8.24

56 to 61

62 to 66

67 to 72

73 to 77

Depth, in meters

1.1 to 2.0

2.1 to 3.0

3.1 to 4.0

4.1 to 5.0

5.1 to 6.0

6.1 to 7.0

Specific conductance, in millisiemens per centimeter

0.425 to 0.451

0.452 to 0.477

0.478 to 0.503

0.504 to 0.529

0.530 to 0.554

0.555 to 0.580

0.581 to 0.606

0.607 to 0.632

Temperature, in degrees Celsius

20.7 to 21.0

21.1 to 21.5

21.6 to 22.0

22.1 to 22.5

22.6 to 23.0

23.1 to 23.5

23.6 to 24.0

Dissolved oxygen, in milligrams per liter

6.6 to 7.0

7.1 to 7.3

7.4 to 7.7

7.8 to 8.1

8.2 to 8.5

8.6 to 8.8

8.9 to 9.2

9.3 to 9.6

Depth-averaged vertical velocity, in centimeters per second

–

0.1 to 1.0

1.1 to 2.0

–4.1 to 4.0 0.9 to 0.0

–3.9 to –3.0

–2.9 to –2.0

–1.9 to –1.0

–

Depth-averaged velocity, in centimeters per second

13 to 15

16 to 18

19 to 21

0.29 to 3.0

3.1 to 6.0

6.1 to 9.0

9.1 to 12

Survey date, September 11–12, 2012

11

12

Shear velocity, in centimeters per second

0.40 to 0.75

0.76 to 0.80

0.81 to 0.85

0.86 to 2.00

Settling possible

Muddy 

 Creek 

 Bay

Flow

0

0

2 4 6 8 10 12

2 4 6 8 10 12

14 KILOMETERS

14 MILES

Ballville

Figure 14. Hydraulic and water-quality data for the Sandusky River, Ohio, September 11 and 12, 2012.
Results 25

0

Time to advect to mouth, in hours

Distance from mouth, in kilometers

Peak

Leading edge

Trailing edge (10 percent)

Mean velocity, 

in centimeters per second 

Freshwater estuary

Potential egg-settling zone

0.01

0.1

1

10

Shear velocity, in centimeters per second

 Egg-settling threshold (just after fertilization)

Egg-settling threshold (2 to 3 hours post fertilization)

Egg-settling threshold (3 to 4 hours post fertilization)

Egg-settling threshold (18–20 hours post fertilization)

u* (Stationary boat, profile fitting)

u* (Moving boat, profile fitting)

u* (Moving boat, Keulegan's relation (1938))

EXPLANATION

Reach traveltime, in hours

B

24.8

21.5

18.9

0 5 10 15 20 25

25

50

75

100

125

150

175

0

5

10

15

20

25

Shallow, swift water

Approximately 35–80 centimeters 

per second mean velocity

Approximately 35–80 centimeters 

per second mean velocity

Freshwater estuary

A

Non-water-hardened

eggs begin to settle

Water-hardened

eggs begin to settle

All Asian carp eggs

begin to settle

Shallow, swift water

C

Ballville Dam Ballville Dam

Figure 15. A, Mean velocity, B, estimated advection time, and C, shear velocity for the Sandusky River, Ohio, 

September 11 and 12, 2012. 
26 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

The transport time from Ballville Dam to the top of the 

potential settling zone is approximately 22 hours for the peak 

of the egg distribution with leading and trailing edge transport 

times of 19 and 25 hours, respectively (fig. 15B). Kocovsky 

and others (2012) predicted a mean summer water temperature 

for the lower Sandusky River of greater than or equal to 24oC, 

and data from this study indicated a water temperature of 21 to 

24oC for mid-September. Continuous water-temperature data 

record at the USGS streamgage on the Sandusky River near 

Fremont, Ohio (04198000), recorded a mean water temperature of 25.1oC for August 2012 (max = 33.1oC and min = 

19.3oC). From figure 7, at 24oC, the hatch time for silver carp 

is approximately 25 hours and for bighead carp is approximately 27 hours with higher temperatures having shorter 

hatching times. Therefore, the traveltime of the eggs from 

Ballville Dam to the settling zone may be sufficiently long to 

allow hatching of at least a portion of the egg mass prior to 

reaching the settling zone during floods of a similar magnitude 

to the study event and average summer water temperatures. 

Additionally, velocity variability within the Sandusky River 

estuary reach due to lake-seiche activity that was not captured 

in this study likely will affect these results (flow variability 

can both hinder and aid the transport of eggs depending on the 

magnitude of the variations and direction of the currents). 

Critical Velocity for Transport of WaterHardened Asian Carp Eggs

Critical shear velocity determines at what point eggs 

will settle; however, mean velocity is generally more widely 

available and more easily calculated. Therefore, the current 

study data can be used to develop a relation between the two 

values and, as a result, determine critical mean velocity values 

for settlement of eggs. The current study data (figs. 9, 11, 13, 

and 15) show that the critical shear velocity at which eggs 

start to sink corresponds to mean depth-averaged velocities in 

the range of 15 to 25 cm/s. These velocities are significantly 

smaller than the 70 cm/s threshold that is commonly reported 

in the literature. The variability in this transport threshold is 

due to difference in the flow depth and substrates in the study 

rivers. Using equation 1 and a shear velocity of 0.75 cm/s, the 

minimum transport velocity for water-hardened Asian carp 

eggs can be plotted as a function of the mean flow depth and 

the bed substrate (fig. 16). The relation derived to generate 

figure 16 assumes that the streambed is flat (no bedforms) and 

free of vegetation (both cause an increase in roughness that 

cannot be accounted for by the median grain size). Therefore, 

a first-order assessment of the transport capability of a river 

for Asian carp eggs can use the mean flow depth and substrate 

type to determine the required minimum flow velocity for 

transport. If mean velocity of a reach does not meet this criterion, it is likely that eggs would settle out of suspension. The 

results from this first-order approach then can be used to guide 

further investigation of hydrodynamics in potential settling 

reaches.

Suggested Future Studies

Although this study increases understanding of how 

hydraulic and water-quality characteristics of rivers contribute 

to their suitability for spawning and transport of Asian carp 

eggs, several areas were identified that warrant further study. 

This study was limited to Great Lakes tributaries without 

Asian carps. It would be valuable to repeat this type of evaluation in areas where Asian carps are spawning and recruiting. 

Comparing results from a spawning reach to the current study 

results would help to verify the developed methodology and 

analysis. An additional limitation of the study was the lack of 

an assessment for nursery habitat, which would be a factor in 

recruitment success. Assessments of rivers with both successful spawning and recruitment of Asian carps would contribute 

to understanding how important this habitat is and where 

it needs to be located to be accessible to the carps. A third 

limitation is the lack of research on the mortality of Asian 

carp eggs. Eggs settled on the bottom of a river generally are 

thought to perish; however, the mechanism of mortality is not 

understood. Further study of how eggs are affected by scour 

and deposition areas in a stream could lead to new control 

technologies. 
Conclusions 27

Depth, in meters 

500

256

64

2

0.0625

0.004

0.00024

102

101

101 100100 10–1

Clay

Silt

Boulders

Cobbles

Gravel

Sand

Grain size, Substrate classification

in millimeters 

Minimum required mean velocity for transport of water-hardened 

Asian carp eggs, in centimeters per second

Figure 16. Theoretical curves for estimating the minimum transport velocity for water-hardened Asian carp eggs from observations 

of mean flow depth and substrate type. This relation assumes the bed contains no bedforms or aquatic vegetation. 

Conclusions

If the invasive Asian carps (bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix) 

migrate to the Great Lakes in spite of the efforts to stop their 

advancement, these species will require the fast flowing water 

of the Great Lakes tributaries for spawning and recruitment in 

order to establish a growing population. This report describes 

the hydraulic and water-quality data-collection effort by the 

U.S. Geological Survey (USGS), in cooperation with the Great 

Lakes Restoration Initiative as administered by the U.S. Environmental Protection Agency, on four Great Lakes tributaries 

and uses new information about egg-transport characteristics 

to provide insight into the spawning and recruitment suitability of these tributaries. As part of this study, two Lake Michigan tributaries (the Milwaukee and St. Joseph Rivers) and 

two Lake Erie tributaries (the Maumee and Sandusky River) 

were investigated to determine if these tributaries, deemed 

to be potential spawning grounds, possess the hydraulic and 

water-quality characteristics to allow successful spawning 

and transport of Asian carp eggs. This study utilized standard 

USGS sampling protocols and instrumentation for hydraulic 

and water-quality measurements, together with differential 

global positioning system data for georeferencing. Non-standard data-processing techniques, combined with laboratory 

analysis of Asian carp egg characteristics, allowed a detailed 

assessment of the transport capabilities of each of these 

four tributaries. This assessment is based solely on analysis 

of observed data and did not utilize the collected data for 

detailed transport modeling (an ongoing, parallel aspect of this 

project).

All four tributaries exhibited potential settling zones for 

Asian carp eggs both within the estuaries and river mouths 

and within the lower 100 kilometers (km) of the river. Dams 

played a leading role in defining these settling zones, with 

the exception of dams on the Sandusky River. The impoundments created by many of the larger dams on these rivers 

acted to sufficiently decelerate the flows and allowed the shear 

velocity to drop below the settling velocity for Asian carp 

eggs, which allowed the eggs to fall out of suspension and 

settle on the bottom where it is thought the eggs would perish. 
28 Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability

While three rivers exhibited these settling zones upstream of 

the larger dams, not all settling zones are likely to have such 

effects on egg transport. The Milwaukee River exhibited only 

a short settling zone upstream of the Grafton Dam, whereas 

the St. Joseph and Maumee Rivers both had extensive settling 

zones (>5 km) behind major dams. These longer settling zones 

are likely to capture more eggs than shorter reaches. In addition, all four tributaries exhibited settling zones at their river 

mouths. However, the Sandusky and Maumee Rivers both had 

large settling zones (11 and 22 km, respectively) that extended 

far up the rivers from the mouth, and the Lake Michigan tributaries exhibited much shorter estuary settling zones. 

While hydraulic data from all four rivers indicated settling of eggs is possible, all four exhibited sufficient temperatures, water-quality characteristics, turbulence, and transport 

times outside of settling zones for successful suspension and 

development of Asian carp eggs to the hatching stage before 

the threat of settlement. This finding indicates that, based on 

observed data, these four Great Lakes tributaries have sufficient hydraulic and water-quality characteristics to support 

successful spawning and transport of Asian carp eggs. More 

generally, the findings indicate that under the right temperature and flow conditions, river reaches as short as 25 km may 

allow Asian carp eggs sufficient time to develop to hatching. 

Additionally, examining the relation between critical shear 

velocity and mean velocity, egg settling appears to take place 

at mean velocities in the range of 15–25 centimeters per second, a much lower value than generally is cited in the literature. Finally, curves are presented for a first-order approach to 

estimating the minimum transport velocity for Asian carp eggs 

from mean flow depth and river-substrate type in the absence 

of bedforms or vegetation. These conclusions would expand 

the number of possible tributaries suitable for Asian carp 

spawning and contribute to the understanding of how hydraulic and water-quality information could be used to evaluate 

additional rivers in the future. Future studies will be needed to 

verify the conclusions of this study in rivers where Asian carp 

are known to spawn and to further explore the mechanisms of 

mortality for the Asian carp eggs.

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Publishing support provided by the U.S. Geological Survey 

Science Publishing Network, 

Columbus Publishing Service Center

For more information concerning the research in this report, 

contact the 

Director, Illinois Water Science Center

U.S. Geological Survey

1201 West University Avenue, Suite 100

Urbana, IL 61801–2347

http://il.water.usgs.gov/
Murphy and Jackson—Investigation of Great Lakes Tributaries, Asian Carp Spawning and Egg-Transport Suitability —Scientific Investigations Report 2013–5106